Generally speaking, machines for making and dispensing ice cream of this kind comprises a tank for containing the basic products, into which the liquid or semi-liquid ingredients (that is, the liquid or semi-liquid basic products) are fed and where the selfsame basic products are processed.
The containment tank internally comprises a mixer for the basic products which guarantees that the basic products are mixed continuously during processing.
The tank is wrapped in coils through which a heat exchange fluid is made to flow. The heat exchange fluid heats or cools the tank and, consequently, the products therein, according to set thermal cycles.
More specifically, during a thermal cycle for pasteurizing the basic products inside the containment tank, the heat exchange fluid heats the containment tank and, consequently, the products therein to temperatures of between 65° and 85° C.
During this thermal cycle, the mixer continuously stirs the products being processed so that the end product has a smooth, homogeneous consistency.
When the pasteurization cycle is over, the product in the tank is cooled and brought to a temperature of around 4° C. suitable for its storage, thereby obtaining the ice cream.
During the product cooling and storage cycle, the heat exchange fluid cools the containment tank and, consequently, the products therein.
In the ice cream production sector, it is known that good and well carried out pasteurization makes a product of high quality.
In machines of known type, as described above, however, it has been found that during the pasteurization of the basic products inside the containment tank, the product in contact with the tank walls, and more specifically, the walls around which the coils for the heat exchange fluid are wrapped, tends to become very hot, despite the continuous action of the mixer.
Localized burning of the basic product may lead to the formation of lumps in the product, which negatively affect the quality of the basic product being processed in terms of smooth, homogeneous consistency, thus producing a poorer quality ice cream.